Crown construction for derricks



Aug. 9, 1932. A. RAWSON 1,870,587

CROWN CONSTRUCTION FOR DERRICKS Filed July 8, 1929 2 Sheets-Sheet 1 I. 40 1, "L. Z6 B 1 INVENTOR.

l l 65/72? A 020.5077 BY %Wm aim A TTORNE YS.

g- 9, 1932- I 1.. A. RAWSON 1,870,587

CROWN CONSTRUCTION FOR DERRICKS Filed July 8, 1929 2 Sheets-Sheet 2 L 65/12? A Jiazuson A TTORNE YS.

Patented Aug. 9, 1932 UNITED stares PATENT @FFIQE LESLIE A. RAWSON, 0 LOS ANGELES, CALIECBIHA, ASSIGNOR T0 EMSCO DERRICK 8:

EQUIPMENT COMPANY, OF 10S ANGELES, CALIFORNIA, A CORPORATION OF CALI- FORNIA.

CROWN CONSTRUCTION FOR DER-KICKS Application filed July 8, 1929.

This invention relates to construction of derricks of the character employed in drilling oil wells and relates particularly to the crown construction of steel derricks.

In the present construction of oil well derricks it is customary to employ four substan tially vertical but inwardly sloping legs or posts which are braced by horizontal and cross bracing members, which support a crown frame at their upper ends. This crown frame is, in the previous types of construction, composed of four members placed to form a rectangle, the ends of the members being secured together by clips which w bolt to two adjacent members or by use of equivalent means.

Under heavy loads to which the derrick is subjected it is found that there is a tendency toward angular displacement of the members forming the crown frame owing to improper or insufficient bracing of the corners, with the result that one side of the crown frame becomes offset relative to the opposite side so as to form a rhombus or rhomboid frame instead of a rectangular frame, this being hazardous in that under such conditions the derrick will collapse when an excessive load is placed thereon.

It is an object of my present invention to provide a crown construction of simple and economical form which may be readily incorporated in the derrick structure and which will hold the corners of the crown frame with ample rigidity to prevent angular disalignment of the members forming the crown frame.

It is a further object of my invention to provide a crown construction for derricks in which the parts constituting the crown construction are relatively positioned and are so secured to the legs of the derrick that twisting action at the crown construction is amply resisted. This object of my invention is accomplished by providing plates secured to the upper ends of each of the legs. The crown. construction is provided in the form of pairs of primary and secondary members, the primary members extending parallel to each other and at right angles to the secondary members, and the secondary 'mern- Serial No. 376,801.

bers extending parallel to each other. The ends of the primary and secondary members are secured together so as to form a rectangular construction. In addition to this, each end of each of the crown members is secured to each of the plates- Each end of the primary crown members is secured to the outer edges of each plate and each end of the secondary crown members is secured to the inner edges of each plate.

My invention not only constitutes the structure defined in the preceding paragraph, but also includes the details of construction, particularly the type of structures from which the crown members are made and the manner in which they are arranged.

Further objects and advantages will be described throughout the following part of the specification.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is an elevational view showing the upper end of a steel derrick equipped with my new crown construction.

Fig. 2 is a side elevation corresponding to Fig. 1 but without showing the crown block supported on the crown frame of the derrick.

Fig. 3 is a section taken substantially on a plane represented by the line 3-3 of Fig. 2.

Fig. a is a perspective view of my improved cap block looking upwardly toward the underside of the horizontal plate and toward the inner faces of the downwardly extending post securing walls of the cap block.

Fig. 5 is an enlarged detail showing in plan view one of the cap blocks with primary and secondary members secured thereto.

As shown in Figs. 1 and 2, my new crown construction for steel derricks includes the upper ends of derrick legs or post members 11 which are placed relative to each other at the four corners of a square or rectangle and sloping inwardly in upward direction so as to give the derrick a pyramidal form. The legs 11 are securely braced in the customary manner by horizontal girts 12, cross bracing angles 13, and intermediate horizontal braces let. At the upper end of each post 11 a cap block 15 is secured, this cap block including an upper horizontal plate portion 16 which is substantially square in outline and provides an upper horizontal face 17.

Parallel to the outer edges 18 and 19 of the plate 16 webs or walls 20 extend downwardly, these webs or walls extending in lanes which are perpendicular to each other but which planes cross on a nearly vertical line which coincides with an outer corner 21 of the post member, generally an angle, thelegsof which are bolted to the walls 20. As shown particularly in Fig. 4, the adjacent edges of the walls 20 are joined by an outwardly curved rib 22 so as to provide an inner groove 23 to give ample clearance for the corner 21 of the post angle, which is bolted against the inner faces of the walls 20. Also downwardly projecting from the plate portion 16 is a vertical web 24 which is curved so as to include end portions 25 and 26 substantially parallel to the inner edges 27 and 28 of the plate portion 16.

For the purpose of securing the cap block 15 to the upper end of the angle constituting a leg or post 11 of the derrick nearly vertical rows of bolt holes 29 are provided through which bolts 30, indicated in Figs. 1 and2, may be inserted, these bolts passing through similarly spaced holes provided in the upper ends of the members 11. In each of the walls 20, at proper angle relative to upper bolt holes 32 of the respective groups of bolt holes 29, a bolt hole 33 is formed so as to be in alignment with the upper end of the cross bracing members 13 which lie across and are secured tothe outer faces of the walls 20, two bolts being employed in the upper end of each cross bracing member 13, as shown in Figs. 1 and 2, the upper outer of which bolts is the upper bolt 34 of a vertical group of bolts 30, and the inner bolt 35 being passed through the angularly spaced hole 33.

Supported on the cap blocks 15 is a crown frame 36 of rectangular form and consisting of a pair of parallel primary cap members 37 and a pair of parallel secondary cap members 38. The primary cap members, as shown in Fig. 1, support the crown block 39 of the derrick, this crown block extending across the members 37 in substantially the manner shown and constituting the upper or stationary portion of the hoisting means through which the load incurred by the lifting of tubing or dril1-pipe and such is transferred to the derrick structure.

In order to carry the heavy loads placed thereon by the crown block 39, the primary cap members 37 are made from structural I-beams, and in order that the loads transferred by the ends of the I-beams 37 shall be centralized with respect to the posts 11 the members 37 are disposed on central axes A-A of the respective plate portions 16 of the cap blocks 15, as particularly shown in Fig. 5.

In the illustration of the invention I have shown the ends of the primary cap members 37 extending centrally with respect to the plate portion 16 over and partly across the upper faces of such plate portions, and in such positions crossing the inner edges 27 of the plate portions 16 but stopping short of the outer edges 19, as best shown in Fig. 5. In this manner the primary members are so disposed that the hoisting loads from the crown block 39 may be most efliciently transferred to the cap blocks 15 and thence to the posts 11 of the derrick.

Across the ends of the primary members 37, ends 40 of the secondar members 38 are extended, as shown best in *igs. 3 and 5, these rimary members being secured by a group of bolts 41 extending through holes 42 suitably provided therefor in lower flanges 43 of the channels forming the secondary members 38 and adjacent to the outer edges of the plate portions 16 of the cap blocks 15. The secondary members 38 are also secured to the ends of the primary members 37 by means of clips 44 which, by use of bolts 45 and 46, are

secured to vertical web portions 47 and 48 of the primary and secondary members 37 and 38.

As shown in Fig. 4, bolt holes 49 are spaced adjacent to the inner edges 27 and V 28 of the plate portions 16 respectivel centralized relative to the axes A-A and B, and as shown in Figs. '3 and 5, bolts 50 are extended through lower flanges 51 of the primary members 37 and through the holes 49 lying thereunder, thus securing the flange portions 51 of the primary members 37 to the respective cap blocks 15.

With reference to Fig. 5, it will be noticed that a plurality of bolts 41, preferably four in number, are used to secure the secon ary members 38 to the cap block 15 and that by such bolting the secondary members 38 are held securely against lateral disalignment in a horizontal plane relative to the plate portions 16 of the cap blocks to which they are respectively secured. The primary members 37 are likewise secured against lateral disalignment in a horizontal plane by having their respective ends secured stationary by reason of the employment of the clips 44 to attach such ends of the primary members to the webs of the secondary members.

The bolts 50 by which the lower flanges 51 of the primarymembers 37 are secured to the cap blocks 15 are spaced a sufficient distance back or inwardly from the respective ends of the primary members 37 to cooperate with the end securing means 44 in holding the primary members 37 rigidly against angular deflection.

By securing the primary and secondary members rigidly to the plate portions 16 of the cap blocks in the manner my invention provides, a very rigid crown frame or water ne r-ass? primary member 37 have ample strength to carry the crown block structure 39 which is supported thereon as shown in Fig. 1. The channels forming the secondary member 38 do not carry vertical loads but cooperate in the forming of a very rigid crown frame structure.

In Fig. 1 I have shown the crown block 39 extending across and supported on the primary members 3? and in such position being disposed on the axis 6-4) of the crown frame shown in Fig. 3. The crown block 39 may be swung around onto the axis a-a if desired by changing the relative position of the prima-ry members 37 and the secondary members 38 so that the primary members 37 will lie across the center line aa instead of across the center line b-Z) as shown, and so that the secondary members 38 will lie across the center line Z)?) instead of across the center line aa. To enable the ready change in the respective positions of these primary and secondary members 37 and 38 the two outer edge portions 18 and 19 of each cap block 15 are provided with a group of holes 42 so that the secondary members 38 may be bolted parallel to either an edge 18 or an edge 19, and the inner edges 27 and 28 of the plate portions 16 of the cap blocks 15 have pairs of holes 49 formed adjacent thereto through which the bolts 50 may be passed in securing the primary members in either of the positions crossing the axis A-A or BB, as previously indicated. This feature of construction is particularly valuable. for the reason that it is at times desired to change the position of the crown block during or after erection of the derrick.

In the invention I have provided a very simple means for securing the crown frame to the top of the derrick structure whereby the hoisting loads transmitted from the crown block may be properly transferred to the derrick structure, which is of such form as to have great rigidity towards disalignment. and which is readily adapted to alternate positions of the respective primary and secondary members whereby to provide a selective positioning of the crown block relative to the major center lines of the derrick.

The most important feature. of my invention is that the crown construction is designed to prevent any twisting action in the crown relative to the legs. It will be readily understood that if a twisting action should occur, the upper ends of the legs would be twisted from rectangular arrangement and caused to form a rhomboid or adiamond-shaped configuration. This obviously would greatly decrease the strength of the derrick and might result in the collapsing of the derrick. The manner in which this feature is provided for has been fully explained, and it briefly consists in the arrangement of the primary and secondary crown members and the manners in which they iare secured to each other and are secured -to the upper ends of the legs of the derrick.

I claim as invention:

1. In crown construction for a derrick: a crown frame consisting of a pair of parallel primary-cap members and 'a pair of parallel secondary cap members, placed to form a rectangle; a post member under each corner of *said-crownframe'; and amp block at the upper end of each post member adapted to support and'secure the ends-of said-cap members, said cap block comprising a plate member including a horizontal upper face, two

outer perpendicular edges,.and two inner perpendicular edges, there 'being'ma'tched groups of primary bolt holes spaced adj acent to said inner perpendicular edges and matched groups of secondary "bolt holes adjacent to said outer perpendicular edges, and means for securing said'p'laite member to the upper end of a derrick post.

2. In a derrick construction, the combination of: four legs in substantially rectangular relationship; cap members :secured to the upper end of said legs, providing horizontal plates; a crown construction supported on said plates, providing primary crown members extending parallel to each other and each engaging two of said plates, secondary crown members extending at right angles to said primary crown members and parallel to each other, and means for securing the ends of each crown member to the adjacent end of another, thus forming a rectangular crown construction; primary securing means for securing each end of said primary crown members, to said plates; and secondary securing means for securing each end of said secondary crown members to said plates.

3. In a derrick construction, the combination of: legs arranged in rectangular relationship; cap members secured to the upper end of each leg, providing horizontal plates, a crown construction supported on said plates providing a pair of parallel channel members placed with their flanges extending horizontally outward and their webs extending vertically, each of said channel members resting on two of said plates, a pair of I- beams arranged parallel to each other but at right angles to said channel members, each of said I-beams being arranged with their flanges extending horizontally and their webs extending Vertically, and each resting on two of said plates, and means for securing together the ends of said channel members and said Lbeams; and means for securing the ends of each of said channel members and said I-beams to said plates.

4. In a derrick construction, the combination of: legs arranged in rectangular relationship; cap members secured to the upper end of each leg, providing horizontal plates; a crown construction supported on said plates, providing a pair of parallel channel members placed with their flanges extending horizontally outward and their Webs extending vertically, each of said channel members 9 resting on two of said plates, a pair of I- beamsarranged parallel to each other but at right angles to said channel members, each of said I-beams being arranged with their flanges extending horizontally and their webs extending vertically, and each resting on two of said plates, and means attached to the Web of each ofsaid channel members and said I- beams for connecting the ends thereof together to form a rectangular structure; primary securing means for securing each end of each of said channel members to each of said plates, bolt means securing the lower flange of each of said channel members to an outer edge of each of said plates, said bolt l means being arranged in a single row on each of said plates; and secondary securing means for securing each end of each of said I- beams to an inner edge of each of said plates. In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 29 day of June, 1929.

LESLIE A. RAVVSON. 

